The present disclosure generally relates to nuclear fuel pellet inspection. More specifically, the present embodiments are directed towards X-ray methods and apparatuses for detecting physical defects in nuclear fuel pellets.
In a typical configuration, fuel for nuclear power plants is often in the form of cylindrical pellets stacked within a cladding tube. The cylindrical pellets typically contain the nuclear fuel material, and the cladding is often composed of a relatively inert substance. Together, these form a nuclear fuel rod which, during operation of the power plant, may be used to drive selected processes for power generation. One example would be steam generation that is used to power a turbine. The manufacturing of such fuel rods is typically performed by stacking the cylindrical pellets inside the cladding tube and welding end plugs onto the end of the cladding tubes.
Nuclear fuel reliability is an issue throughout the nuclear industry and is a key objective in many fuel rod manufacturing processes. Nuclear fuel pellet defects can lead to a variety of fuel performance deficiencies, among other problems. For example, pellets missing a portion of their cylindrical surface (e.g., a pit or chip), cracks, and other defects may lead to pellet-cladding interaction (PCI) in which the fuel pellet contacts the cladding resulting in stress, which may be accompanied by corrosive compounds that attack the cladding and can result in cladding rupture. Such fuel rod failures can allow highly radioactive contaminants to be dispersed in the reactor coolant. Such events can lead to higher than desired radiation exposure to power plant operators and to unplanned shutdowns of the reactor to remove and replace the failed fuel. Such unplanned outages can lead to significant financial and/or capital losses to both the energy provider and their customers.